1. Field of the Invention
This invention relates to intravascular access devices, and more particularly, to a wireless high flow sheath introducer for intravascular access and a method for using such an introducer.
2. Description of Related Art
There are several methods for introducing a catheter into a blood vessel. In general, in order to introduce a catheter into a blood vessel through the skin, the practice in the prior art is to use an introducing needle, a guidewire, and a dilator (this technique is commonly referred to as the "Seldinger Technique"). More specifically, the introducing needle (which may compromise an inner needle portion and a cover tube, or alternatively, just the needle portion) is used to pierce the desired blood vessel. In the instance where both the inner needle portion and a cover tube are used, the inner needle portion is withdrawn. The guidewire is then inserted into the blood vessel by passing it through the cover tube. In the instance where only the needle portion is used, the needle is left in place, and the guidewire is then inserted into the blood vessel by passing it through the needle. This is followed by withdrawing the cover tube or the needle, leaving the guidewire in place. Next a dilator is introduced so as to fit over the guidewire. The dilator functions to dilate the opening made in the subcutaneous tissue and in the wall of the blood vessel, thus, making it possible to reduce resistance which the catheter would otherwise meet in being inserted through the subcutaneous tissue and the blood vessel wall. Next, the dilator is withdrawn from the guidewire and a catheter is fitted over the guidewire so that the catheter may be then introduced into the blood vessel.
The conventional method described above is disadvantageous, especially in emergency situations, in that the preparation and handling of the instruments is of some complexity. The Seldinger Technique is time consuming and requires the use of an introducing needle, which makes it possible to insert a guidewire into the blood vessel so that the catheter can be introduced into the blood vessel through the skin, as well as a dilator for spreading the subcutaneous tissue and the opening in the blood vessel wall to facilitate the introduction of the catheter. The procedure requires a large sterile field to prevent contamination and introduction of infection during insertion and removal of the multiple parts.
The problem of properly introducing a catheter into a blood vessel becomes more acute in emergency situations, where the catheter must be introduced quickly and sterilely and where a high-flow rate is required. For example, intravenous access is a vital step in the resuscitation of patients in hypovolemic shock. Until recently, plastic over-the-needle catheters were used for peripheral venous insertion, and plastic catheters placed through needles (intercaths) were used for insertion into the central venous circulation. Recently, it has been recognized that these catheters often do not infuse fluids at a high enough flow rate for the resuscitation of severely hypovolemic patients.
In addition to being used for the placement of intravascular catheters, the Seldinger Technique is also used for the introduction of "catheter introducers". These introducers are placed in the vessel so that catheters can be moved in and out of the vessel without losing patency between the skin and blood vessel, and eliminate the need to reintroduce a guidewire. These "catheters introducers" are introduced over a guidewire as previously described. However, the "catheter introducer" is coaxially loaded over the dilator for insertion. The dilator extends approximately two to three centimeters distal to the "catheter introducer". Thus, the dilator with the catheter introducer loaded over it is advanced over the guidewire through the subcutaneous tissue and into the vessel. Initially, only the dilator is advanced to make a hole of sufficient size to allow introduction of the "catheter introducer". Then, the dilator is further advanced until both the dilator and "catheter introducer" are in the blood vessel. The guidewire and dilator are then removed, leaving the "catheter introducer" in the vessel. Thus, patency between the skin and the lumen of the vessel is guaranteed. Catheters of various sizes and lengths can be introduced through the "catheter introducer" and can be changed without losing patency of the vessel.
It was soon recognized that these large bore "catheter introducers" could be placed in vessels to allow the infusion of large volumes of fluid at very high flow rates. Recently, high flow, large bore peripheral sheaths, similar to catheter introducers, have been developed. These high flow large bore sheaths are designed for placement by the Seldinger Technique. These sheaths deliver flow rates between 2.5 and 5 times greater than catheters previously used for peripheral and central infusions.
Unfortunately, many physicians are unskilled inthe Seldinger Technique of placing a sheath over a guidewire. It has become evident that the lack of sufficient psychomotor skill limits the use of these new high flow devices to physicians with previous experience in inserting devices over guidewires. It therefore would be advantageous to provide a high flow catheter introducing instrument that does not require placing a sheath over a guidewire. The present invention provides such an instrument and a method for using such an instrument. Additionally, the present invention provides an instrumental that can be rapidly placed in peripheral vessels without the necessity of a large sterile field, which is needed when high flow catheters are placed over guidewires. Thus, the present invention provides an instrument which is ideal for use in emergency conditions where large sterile fields are rarely possible.